The plan is to put black-theme movies in commercial theaters, initially from the independent film program recently begun by the AMC theater chain, for a two-week run supported by social networks, mailing lists and other buzz-building services at the disposal of allied ethnic film festivals.

A second film, and three more cities — Chicago, Boston and Nashville — are expected to follow in August.

And if Ms. DuVernay is correct in her belief that African-American viewers want more movies than they are getting from conventional distributors, the movement will eventually reach about four dozen cities where black-oriented festivals have been gaining strength, even as black film languishes in the studio world.

Speaking over espresso and hot chocolate at the Four Seasons Hotel in Beverly Hills last week, Ms. DuVernay, 38, who helped market studio films like “Dreamgirls” and “Invictus,” described the new alliance, which she organized, as being less a business than a “call to action.”

Those who make specifically black-theme movies, she said, should realize that “no one is ever going to care about their film except the people it’s made for, which is, black folks.”

According to a 2009 survey of moviegoing compiled for the Motion Picture Association of America, African-Americans, about 12 percent of the North American population, accounted for only 11 percent of ticket sales and less than 9 percent of frequent moviegoers. (By contrast, Hispanics, who make up 15 percent of the population, bought 21 percent of tickets, according to the study.)

By some accounts, that is because the black film world is shrinking.

Stacy Spikes, a former Miramax Films executive who is the founder and chief executive of the Urbanworld festival, is one of several executives who said the distribution of black-theme films began to evaporate in the last five years. That happened, he said, as New Line Cinema, Warner Independent Pictures, Metro-Goldwyn-Mayer and other companies that had specialized in midbudget comedies and dramas shrank or disappeared.

Films in a long-running Tyler Perry series have continued to do well — Mr. Perry’s “Why Did I Get Married Too?” brought in $60 million in domestic ticket sales for Lionsgate last year, and was the best-performing black-theme film of 2010. For the most part, though, movies by black filmmakers with a largely black cast barely registered at the box office.

As recently as 2002, the success of “Barbershop,” which cost a little more than $10 million to make and took in nearly $76 million at the domestic box office for MGM, seemed to point toward a resurgence in black-theme films. Chris McGurk, who was then vice chairman of MGM, even tried to position the studio as a gathering point for black filmmakers.

An error has occurred. Please try again later.

You are already subscribed to this email.

But the strategy faltered, Mr. McGurk said, as costs rose, and black-theme films, which generally underperform in foreign markets, outgrew their niche. “The economics of that business really only work if you’re able to produce them for $10 million or less,” he explained.

Told of Ms. DuVernay’s new alliance, Mr. McGurk, who is now the chief executive of Cinedigm Digital Cinema Corporation, said, “They’re doing the right thing.” Low budgets and precise marketing, he said, are critical to reviving the genre.

Others warn that great passion and a festival network cannot match the power of a well-heeled studio distribution mechanism. And Ms. DuVernay acknowledges that her alliance can do little more than get a picture on screens; turning a profit will depend on what happens to a film at additional theaters and in home entertainment markets after its brief introduction.

Still, Mr. Spikes said, filmmakers and studios could learn something from glad-handing politicians, who have long used networking and physical presence to build support. Films distributed by the new alliance, he said, will be backed by directors and stars who are willing “to go on the road and do that heavy-lifting” with festival-style appearances at screenings.

As opportunity diminished in feature films, Mr. Spikes noted, black actors and filmmakers — like more than a few white counterparts — have turned increasingly to television. He cited Regina King, who plays the detective Lydia Adams on “Southland,” as someone who was once better known for her work in feature films like “Boyz N the Hood,” “Poetic Justice” and “How Stella Got Her Groove Back.”

Yet this year’s Sundance Film Festival has a strong run of work by black filmmakers, including “Pariah,” about the struggles of a Bronx teenager, from the writer and director Dee Rees, and “Gun Hill Road,” another Bronx tale, written and directed by Rashaad Ernesto Green.

John Cooper, the Sundance festival’s director, said his programmers had not consciously reached for black-centered films but came up with a bumper crop anyway. “It’s almost natural selection,” Mr. Cooper said. He noted, however, that almost all of those films arrived without distributors.

When Sundance gets under way in Park City, Utah, on Jan. 20, Ms. DuVernay said she would be there to introduce her alliance with a couple of filmmaker dinners. And she applauds Mr. Cooper for having put the spotlight on at least a dozen black-theme pictures at this year’s event.